The invention relates to a process for producing precise cut surfaces on a workpiece by stamping or blanking, in particular by fine-edge blanking, a contour first being stamped or blanked out at a distance from the actual contour of the workpiece, and the workpiece then being scraped down to its final contour.
Although in the present case the description relates essentially to so-called fine-edge blanking, the invention is also intended to encompass a normal stamping operation, in which the process according to the invention may be used.
Unlike in normal stamping, fine-edge blanking makes it possible to produce parts which have a cut surface which is almost 100% smooth. Even when fine-edge blanking, process conditions mean that there is an edge reduction on the component cut surface which faces the cutting tip and a burr on the side opposite to the edge reduction. This edge reduction and burr is dependent mainly on the geometric shape of the component, but also on the material and the thickness of the component. They are considerably larger with a projecting corner than with a reentrant corner. The major advantage of a component produced by the fine-edge blanking process consists, in addition to the smooth cut surface, in the fact that the component cut surface is hardened.
For functional shapes of fine-edged blanks, there is a recurring need for only a slight or small edge reduction. The projecting, acute-angled shapes of the fine-edged blanks have a large reduction, such as for example pawl teeth or gear wheels. An edge reduction produced at the cut surface of a fine-edged blank and a burr situated on the opposite side from the edge reduction are removed by shaving. This results in an enlarged bearing portion of the functional area; this means that the component can be subjected to higher loads or, if the loading level is predetermined, thinner sheet thicknesses can be used.
By way of example, CH 665 367 A2 describes a shaving process in which the shaving is carried out in the cutting direction, or counter to the cutting direction, of the preceding fine-edge blanking operation. This means that the actual desired contour of the workpiece to be produced is approached in a number of steps. The significant disadvantage which has emerged for this process is that the shaving produces chips which remain in the tool or in the press, and over the course of time these lead to considerable operating problems.